Yes, this is a bug, we are able to reproduce it. In fact, the box component is basically considered to be used widely in xyLayout since in tableLayout logic, you will not able to place/display any component inside of a box component.

I registered a ticket regarding this problem, thanks for the feedback again.

Currently, we are not planning to implement this feature in the near future. As an alternative solution, to put your components inside of a box in a tableLayout structure, you can place them into a separate panel and set "LineBorder" as the borderType of this panel to simulate the box view.